gpio: Add GPIO support for the WinSystems WS16C48

The WinSystems WS16C48 device provides 48 lines of digital I/O. In
addition, the first 24 lines may be used for interrupt-handled edge
detection; rising edge detection and falling edge detection are
supported.

This driver provides GPIO and IRQ support for these 48 channels of
digital I/O. The base port address for the device may be configured via
the ws16c48_base module parameter. The interrupt line number for the
device may be configured via the ws16c48_irq module parameter.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index c88dd24..b5337f2 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -570,6 +570,15 @@
 	  blocks of the TS-5500: DIO1, DIO2 and the LCD port, and the TS-5600
 	  LCD port.
 
+config GPIO_WS16C48
+	tristate "WinSystems WS16C48 GPIO support"
+	select GPIOLIB_IRQCHIP
+	help
+	  Enables GPIO support for the WinSystems WS16C48. The base port address
+	  for the device may be configured via the ws16c48_base module
+	  parameter. The interrupt line number for the device may be configured
+	  via the ws16c48_irq module parameter.
+
 endmenu
 
 menu "I2C GPIO expanders"